The present disclosure relates to a sheet post-processing apparatus which performs post-processing such as binding processing and shift discharge processing on sheets, such as paper sheets, on which images have been formed by an image forming apparatus, such as a copier, a facsimile machine, a printer, etc., and an image forming system including the same.
Conventionally, sheet post-processing apparatuses are used which are capable of performing sheet post-processing, such as binding processing of stacking, as a paper sheet bundle, a plurality of paper sheets (sheets) on each of which an image has been formed by an image forming apparatus such as a copier, a printer, etc., and binding the stacked paper sheet bundle by means of a stapler, punch-hole forming processing of punching a hole (perforation) by means of a punch-hole forming device, and shift discharge processing of discharging paper sheet bundles each including a predetermined number of paper sheets to positions shifted from each other.
In such a sheet post-processing apparatus, there are provided a processing tray on which a paper sheet on which an image has been formed is loaded, a discharge tray disposed on a downstream side of the processing tray in a sheet conveyance direction, and a discharge roller pair which discharges the paper sheet on the processing tray onto the discharge tray. With such a configuration, on the processing tray or the like, the binding processing and the shift discharge processing, etc. are performed. Further, there is also known an image forming apparatus provided with a shift member which moves a paper sheet bundle in a sheet width direction in order to align a side end of the paper sheet bundle on the processing tray before the binding processing, or in order to perform the shift discharge processing.